Compromised account

Thank you for your previous response regarding U.S. Airways being in the "from" section of my emails instead of my name. I have changed the password. However, I can't seem to change the identity questions. I would much prefer NOT to change my email address if I can avoid it. I use Yahoo email and Mozilla browser. Is there anything further I can do? Would it change anything if I used Internet Explorer as my browser? Please advise... HELP!!! Thank you!